Semiconductor devices are normally distributed in a state where a semiconductor chip is sealed (packaged) together with bonding wires by a resin. Inside the package, electrode pads of the semiconductor chip are electrically connected by the bonding wires to electrode leads that are partially exposed from the resin package. Electrical connection of the semiconductor chip and a mounting board is thus achieved by connecting the electrode leads as external terminals to wirings on a mounting board.
Although conventionally, gold wires are mainly used as the bonding wires connecting the electrode pads and the electrode leads, recently, the use of copper wires that are cheaper than gold wires is being examined for reducing the use of high-priced gold.